1. Field of the Invention
The present invention generally relates to an angle detection apparatus and method for a rotor of a motor, in particular, to an angle detection apparatus and method for a rotor of a Brushless Direct Current (BLDC) motor.
2. Description of Related Art
Referring to FIG. 1, FIG. 1 is a block diagram of an angle detection apparatus 100 for a rotor of a motor in the prior art. A conventional angle detection apparatus 100 for a rotor of a BLDC motor includes a sampler 110, a divider 120, and a counter 130. The sampler 110 receives a rotor sensing signal HAOUT generated by a Hall sensor module on a rotor of a motor. The rotor sensing signal HAOUT is a periodic signal having a plurality of pulses. The sampler 110 samples a time distance between two adjacent pulses of the rotor sensing signal HAOUT through a high frequency clock signal, and calculates a time range T60 between the two adjacent pulses of the rotor sensing signal HAOUT by using a sampled result (the number of the clock signals included in the time range between the two pulses).
The divider 120 is coupled to the sampler 110, performs a division operation on the received time range T60 to generate a step time Tstep, and provides the step time Tstep to the counter 130. The counter 130 calculates an angle ANG-OUT of the rotor according to the rotor sensing signal HAOUT by using the step time Tstep.
Referring to FIG. 1 and FIG. 2, FIG. 2 is a schematic view of the counter 130 using the step time Tstep to calculate the angle ANG-OUT of the rotor. The resolution of a step time Tstep is limited, and when a time range WTH is not an integer multiple of the step time Tstep, the counting action of the counter 130 has an error ERR. The error ERR is accumulated continuously when the rotor of the motor runs continuously. That is to say, as the motor operates longer, the accuracy of the angle detection for the rotor of the motor gets poorer.